Power Control Method for Vertical Pumping Unit

ABSTRACT

The present disclosure provides a power control method for a vertical pumping unit. A whole stroke of the vertical pumping unit is divided into four running stroke sections of upper-range upward, upper-range downward, lower-range downward and lower-range upward. Every time when a motor control system receives a neutral position signal, at least one upward or downward motor running parameter is converted according to a specified stroke setting of an upper half range or a lower half range, and reversing is implemented after running according to at least one specified stroke parameter is completed or one of an upper position signal and an lower position signal is triggered. When another neutral position signal is received again, the motor control system automatically performs zero position calibration.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present disclosure is filed based upon and claims benefit of Chinese Patent Application No. 201810752628.5, filed on 2018 Jul. 10, the contents of which are hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a power control method, and in particular to a power control method for a vertical pumping unit.

BACKGROUND

Vertical pumping units are common pumping units for oilfields in China, most of driving systems of the vertical pumping units adopt belt or chain transmission, weight boxes and pumping unit load ends are also mostly connected through load belts, and there may exist elastic extension and retraction in a long-stroke running process. An existing control method for a vertical pumping unit is low in intelligence, and parameters of a stroke, a stroke frequency, a speed ratio and the like of the pumping unit may not be timely modified in a running process of the pumping unit. For few vertical pumping units, although strokes may be regulated, upper and lower running ranges may not be selected according to a type of a down hole pump and a stroke change brought by an elastic link such as a belt may not be compensated, which brings influence to pumping efficiency of the pumping unit and is unfavorable for management and maintenance of the vertical pumping units.

SUMMARY

In an embodiment of the present disclosure, a power control method for a vertical pumping unit is provided, a pumping unit load end of the vertical pumping unit being driven by a motor of a driving system to reciprocate for an upward stroke and a downward stroke, the control method including that:

setting at least one initialization parameter of the motor for controlling the pumping unit load end to start running from an initial position; when the pumping unit load end runs to a midpoint position of the upward stroke or a midpoint position of the downward stroke, generating a neutral position signal; under triggering of the neutral position signal, clearing a numerical value of a counter configured to count running strokes of the motor, and adopting the counter to perform recounting to obtain at least one required running stroke parameter of the motor according to a preset required running distance value of the pumping unit load end; and controlling the motor to start running according to the at least one required running stroke parameter of the motor.

In an optional embodiment, the method further includes: when the pumping unit load end runs to a forced reversing position at a predetermined distance away from a limit position of the upward stroke, controlling a pumping unit position sensor system to generate an upper position signal, or, when the pumping unit load end runs to a forced reversing position at the predetermined distance away from a limit position of the downward stroke, controlling the pumping unit position sensor system to generate a lower position signal.

In an optional embodiment, the method further includes: when controlling the motor to start running according to the at least one required running stroke parameter of the motor, determining whether the pumping unit position sensor system generates the upper position signal or the lower position signal or not.

In an optional embodiment, the method further includes: when determining that the pumping unit position sensor system generates the upper position signal or the lower position signal, controlling the motor to execute a forced reversing operation according to the upper position signal or the lower position signal.

In an optional embodiment, the method further includes: when determining that a running position of the pumping unit load end does not reach a position of the upper position signal or the lower position signal, controlling the motor to be reversed for running after completing running according to the at least one required running stroke parameter of the motor.

In an optional embodiment, the method further includes: after setting the at least one initialization parameter for controlling the pumping unit load end to start running from the initial position, determining whether the pumping unit position sensor system generates the upper position signal or the lower position signal or not; when determining that the pumping unit position sensor system does not trigger the upper position signal or the lower position signal and when the pumping unit load end runs to the midpoint position of the upward stroke or the midpoint position of the downward stroke, controlling the pumping unit position sensor system to generate a neutral position signal; and when determining that the pumping unit position sensor system generates the upper position signal or the lower position signal, controlling the motor to execute the forced reversing operation according to the upper position signal or the lower position signal.

In an optional embodiment, the method further includes: when the pumping unit load end runs to the limit position of the upward stroke, controlling the pumping unit position sensor system to generate an upward limit position signal, or, when the pumping unit load end runs to the limit position of the downward stroke, controlling the pumping unit position sensor system to generate a downward limit position signal.

In an optional embodiment, the method further includes: controlling the vertical pumping unit to be forcibly de-energized according to the upward limit position signal or the downward limit position signal.

In an optional embodiment, the method further includes: dividing the upward stroke into a lower-range upward running stroke section and an upper-range upward running stroke section according to the midpoint position of the upward stroke.

In an optional embodiment, the method further includes: dividing the downward stroke into an upper-range downward running stroke section and a lower-range downward running stroke section according to the midpoint position of the downward stroke.

In an optional embodiment, the method further includes: the required running distance value of the pumping unit load end being a distance value in the upper-range upward running stroke section or a distance value in the lower-range downward running stroke section.

In an optional embodiment, setting the at least one initialization parameter for controlling the pumping unit load end to start running from the initial position includes: setting at least one running parameter of the motor and at least one stroke parameter of the vertical pumping unit, the at least one stroke parameter including the distance value in the upper-range upward running stroke section and the distance value in the lower-range downward running stroke section; and controlling the motor to run according to the at least one running parameter and driving, through a mechanical transmission device of the pumping unit, the pumping unit load end to run, the mechanical transmission device including a belt, a gear speed reducer and a chain transmission system.

In an optional embodiment, generating the neutral position signal when the pumping unit load end runs to the midpoint position of the upward stroke or the midpoint position of the downward stroke includes one of the followings: when the pumping unit load end runs to the midpoint position of the upward stroke, generating an upward neutral position signal, and entering the upper-range upward running stroke section; and when the pumping unit load end runs to the midpoint position of the downward stroke, generating a downward neutral position signal, and entering the lower-range upward running stroke section.

In an optional embodiment, under triggering of the neutral position signal, clearing the numerical value of the stroke counter and adopting the stroke counter to perform recounting to obtain the at least one required running stroke parameter of the motor according to the required running distance value of the pumping unit load end includes one of the followings: under triggering of the upward neutral position signal, clearing the numerical value of the stroke counter and adopting the stroke counter to perform recounting to obtain the at least one required running stroke parameter of the motor according to the distance value of the pumping unit load end in the upper-range upward running stroke section; and under triggering of the downward neutral position signal, clearing the numerical value of the stroke counter and adopting the stroke counter to perform recounting to obtain the at least one required running stroke parameter of the motor according to the distance value of the pumping unit load end in the lower-range downward running stroke section.

In an optional embodiment, controlling the motor to start running according to the at least one required running stroke parameter of the motor includes one of the followings: controlling the motor to start running according to the at least one required running stroke parameter of the motor, and controlling the motor to be reversed to enter the upper-range downward running stroke section after completing running according to the at least one required running stroke parameter or under triggering of the upper position signal; and controlling the motor to start running according to the at least one required running stroke parameter of the motor, and controlling the motor to be reversed to enter the lower-range upward running stroke section after completing running according to the at least one required running stroke parameter or under triggering of the lower position signal.

In an optional embodiment, at least one of the neutral position signal, the upper position signal and the lower position signal, an upward limit position signal and a downward limit position signal is generated through the pumping unit position sensor system.

In an optional embodiment, the method further includes: acquiring a first circumferential azimuth signal of an upper sprocket shaft of a driving system in a rotating process; and calculating a stroke position of the pumping unit load end according to the first circumferential azimuth signal and a rotation direction of the motor.

In an optional embodiment, the method further includes: acquiring a second circumferential azimuth signal of a gear in a transmission relationship with the upper sprocket shalt in the rotating process; and calculating the stroke position of the pumping unit load end according to the second circumferential azimuth signal and the rotation direction of the motor.

In an optional embodiment, the motor is a stepless speed regulation motor that is reversed for reciprocation.

In an optional embodiment, the at least one running parameter of the motor is transmitted, monitored and regulated through a remote communication control component.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings forming a part of the application in the specification are adopted to provide a further understanding to the present disclosure. Schematic embodiments of the present disclosure and descriptions thereof are adopted to explain the present disclosure and not intended to form improper limits to the present disclosure. In the drawings:

FIG. 1 is a structural schematic diagram of a vertical pumping unit to which a control method is applied according to an embodiment of the present disclosure.

FIG. 2 is a structural schematic diagram of a position sensor system according to an optional embodiment of the present disclosure.

FIG. 3 is a workflow chart of a control method according to a first optional embodiment of the present disclosure.

FIG. 4 is a workflow chart of a control method according to a second optional embodiment of the present disclosure.

FIG. 5 is a workflow chart of a control method according to a third optional embodiment of the present disclosure.

DETAILED DESCRIPTION

It is to be noted that the embodiments in the present disclosure and characteristics in the embodiments may be combined without conflicts. The present disclosure will be described below with reference to the drawings and in combination with the embodiments in detail.

The present disclosure will further be described below in combination with specific embodiments in detail, and these embodiments may not be understood as limits to the scope of protection of the present disclosure. Term “include” is used to represent existence of a characteristic and a step, but does not exclude existence or addition of one or more other characteristics and steps.

A control method stated in at least some embodiments of the present disclosure is applied to a vertical pumping unit. The vertical pumping unit may include a rope pulley transmission type pumping unit or a chain transmission type pumping unit. FIG. 1 is a structural schematic diagram of a vertical pumping unit to which a control method is applied according to an embodiment of the present disclosure. As shown in FIG. 1, the vertical pumping unit includes a rack 22, a driving system (including a motor 17) providing power for the vertical pumping unit, a transmission system (for example a chain transmission system 3 including a traveling sprocket/balance box device 5) supported by the rack 22 and a motor control system 6 controlling the driving system. The transmission system may include, but not limited to, a driving sprocket, driven sprockets, an upper traveling sprocket, a lower traveling sprocket, a transmission chain and a balance box device. Both of the upper traveling sprocket and the lower traveling sprocket are positioned on the balance box device 5, and an upper end of the transmission chain is fixed at a top of the rack 22. The transmission chain is sequentially wound on the upper traveling sprocket, the driven sprockets, the driving sprocket and the lower traveling sprocket, and is fixed at a lower end of the rack 22. The balance box device 5 is connected with a hanging load of a pumping unit load end through a load belt 13, and the balance box device 5 and the hanging load are positioned on two sides of a drum 12 at the top of the rack 22 respectively. The motor 17 of the driving system drives the driving sprocket to rotate. The driving sprocket rotates counterclockwise to drive the chain mounted on the driving sprocket to move, and the chain drives an upper driven sprocket to rotate clockwise and drives a lower driven sprocket to rotate clockwise. Since two ends of the chain are fixed, the whole balance box device 5 moves upwards along the rack 22, and the pumping unit load end connected with the balance box device 5 moves downwards through the belt to enter a well. After the pumping unit load end reaches a specified position, the motor is controlled to rotate reversely. The driving sprocket rotates reversely to drive the balance box device 5 to move downwards and lift the pumping unit load end through the load belt 13 to complete an oil extraction process, and a next oil extraction cycle is entered. The pumping unit load end of the vertical pumping unit is driven by the motor 17 of the driving system to reciprocate for an upward stroke and a downward stroke to complete oil exploitation and lifting.

In a working process of the vertical pumping unit, the pumping unit load end reciprocates. The pumping unit load end runs upwards to form the upward stroke, and the pumping unit load end runs downwards to form the downward stroke. One upward stroke and one downward stroke form one running stroke. Taking a midpoint position of the upward stroke as a boundary, in the upward stroke, when the pumping unit load end gets close to the midpoint position, the pumping unit load end runs in a lower-range upward running stroke section, and when the pumping unit load end gets far away from the midpoint position, the pumping unit load end runs in an upper-range upward running stroke section. Similarly, taking a midpoint position of the downward stroke as a boundary, in the downward stroke, when the pumping unit load end gets close to the midpoint position, the pumping unit load end runs in an upper-range downward running stroke section, and when the pumping unit load end gets far away from the midpoint position, the pumping unit load end runs in a lower-range downward running stroke section. Thus it can be seen that a cyclic working sequence of the pumping unit load end is the upper-range upward running stroke section—the upper-range downward running stroke section—the lower-range downward running stroke section—the lower-range upward running stroke section—the upper-range upward running stroke section. In the upward stroke, the pumping unit load end is at the midpoint position at the end of the lower-range upward running stroke section. In the downward stroke, the pumping unit load end is at the midpoint position at the end of the upper-range downward running stroke section.

FIG. 2 is a structural schematic diagram of a position sensor system according to an optional embodiment of the present disclosure. As shown in FIG. 2, the position sensor system includes an upper sprocket 1, a neutral position (zero position) sensor 2, a position proportional speed reducer 3, a lower position travel switch contact 4, a position sensor triggering device 5, an upper position travel switch contact 6, an upper position sensor 7, an upper position travel switch 8, a proximity switch bracket 9, a position indicator dial 10, a lower position sensor 11, a lower position travel switch 12, and an upper sprocket shaft (not shown in the figure).

FIG. 3 is a workflow chart of a control method according to a first optional embodiment of the present disclosure. As shown in FIG. 3, the control method of the present disclosure mainly includes the following steps: an initialization step S1, a neutral position signal triggering step S2, a pulse determination step S3 and a running step S4.

At the initialization step S1, at least one initialization parameter for running of a pumping unit is required to be set, thereby enabling a pumping unit load end to start running from an initial position. The step may include the following steps.

At a parameter setting step, at least one running parameter of a motor and at least one stroke parameter of the vertical pumping unit are set, and the at least one stroke parameter includes a distance value of the pumping unit load end in an upper-range upward running stroke section and a distance value in a lower-range downward running stroke section.

At a running starting step, the motor is controlled to run according to the at least one running parameter and drive the pumping unit load end to run.

In an optional embodiment, a neutral position signal is calibrated, that is at least one required running stroke parameter of the motor in a next stroke is calculated every time when the pumping unit load end runs to a midpoint position of an upward stroke or a midpoint position of a downward stroke, and running strokes are counted from zero. It can be seen that calibration may be performed twice for each stroke, so that running accuracy of the pumping unit load end is improved.

At the neutral position signal triggering step S2, when the pumping unit load end runs to the midpoint position of the upward stroke or the midpoint position of the downward stroke, a neutral position signal is generated.

At the pulse determination step S3, under triggering of the neutral position signal, a numerical value of a stroke counter configured to count at least one running stroke parameter of the motor is cleared, and the stroke counter is adopted to perform recounting to obtain at least one required running stroke parameter of the motor according to a preset required running distance value of the pumping unit load end.

At the running step S4, the motor is controlled to start running according to the at least one required running stroke parameter of the motor.

When the pumping unit load end is in the upward stroke and after the neutral position signal triggering step S2 is executed, the pumping unit load end may enter the upper-range upward running stroke section, and the preset required running distance value of the pumping unit load end at the stroke parameter determination step S3 is the distance value in the upper-range upward running stroke section.

When the pumping unit load end is in the downward stroke and after the neutral position signal triggering step S2 is executed, the pumping unit load end may enter the lower-range downward running stroke section, and the preset required running distance value of the pumping unit load end at the pulse determination step S3 is the distance value in the lower-range downward running stroke section.

In a running process of the pumping unit, dead point positions exist in both of the upward stroke and the downward stroke. If the pumping unit load end runs beyond a dead point position, components in the pumping unit may collide to cause a mechanical failure, so that a running distance value of the pumping unit load end has a limit value. The required running distance value of the pumping unit load end at the stroke parameter determination step S3 is set in S1. And if the set value is greater than the limit running distance value of the pumping unit load end, a practical running distance value of the pumping unit load end is greater than the limit distance value, which may cause the failure of the pumping unit. For avoiding the failure, a forced reversing operation is required to be executed before the pumping unit load end runs to a limit position of the upward stroke or a limit position of the downward stroke. For implementing the forced reversing operation, the following step is further included.

At an upper/lower position signal triggering step, when the pumping unit load end runs to a forced reversing position at a predetermined distance away from a limit position of the upward stroke, a pumping unit position sensor system generates an upper position signal is generated. Or, when the pumping unit load end runs to a forced reversing position at the predetermined distance away from a limit position of the downward stroke, the pumping unit position sensor system generates a lower position signal.

The running step S4 includes an upper/lower position signal determination step S40, a pulse control reversing step S41 and a forced reversing step S42.

At the upper/lower position signal determination step S40, whether the pumping unit position sensor system generates the upper position signal or the lower position signal or not is determined.

When determining that the pumping unit load end triggers the pumping unit position sensor system to generate the upper position signal or the lower position signal, the forced reversing step S42 is executed at first, and then the next step, i.e., the neutral position signal triggering step S2, is executed, thereby entering a cyclic working process. In the forced reversing step S42, the motor is controlled to execute the forced reversing operation according to the upper position signal or the lower position signal.

When determining that the pumping unit load end does not trigger the pumping unit position sensor system to generate the upper position signal or the lower position signal, the stroke control reversing step S41 is executed. At the stroke control reversing step S41, the motor is controlled to be reversed for running after completing running according to the required running stroke obtained at the stroke parameter determination step S3. Then, the next step, i.e., the neutral position signal triggering step S2, is executed, thereby entering the cyclic working process.

Under a normal condition, when the pumping unit runs for the first time, the pumping unit load end gets close to the midpoint position from the initial position. Of course, there also exists the condition that the pumping unit load end gets far away from the midpoint position for running. Under this condition, the pumping unit load end triggers the pumping unit position sensor system to generate the upper position signal or the lower position signal at first. In an optional embodiment, after the initialization step S1, the method further includes a first signal determination step S10. At the first signal determination step S10, whether the pumping unit position sensor system generates the upper position signal or the lower position signal or not is determined.

When determining that the pumping unit position sensor system does not generate the upper position signal or the lower position signal, the neutral position signal triggering step S2 is executed.

When determining that the pumping unit position sensor system generates the upper position signal or the lower position signal, the forced reversing step S42 is executed at first, and then the neutral position signal triggering step S2 is executed. At the forced reversing step S42, the motor is controlled to execute the forced reversing operation according to the upper position signal or the lower position signal.

In the running process of the pumping unit, a failure may occur to cause that all of the upper/lower position signal triggering step S40, the forced reversing step S42 and the pulse control reversing step S41 are not executed and the pumping unit load end runs to the dead point position. Under this condition, a limit position signal triggering step S5 is executed at first, and then a forced de-energizing step S6 is executed.

At the limit position signal triggering step S5, when the pumping unit load end runs to the limit position of the upward stroke, the pumping unit position sensor system generates an upward limit position signal. Or, when the pumping unit load end runs to the limit position of the downward stroke, the pumping unit position sensor system generates a downward limit position signal.

At the forced de-energizing step S6, the whole pumping unit is controlled to be forcibly de-energized according to the upward limit position signal or the downward limit position signal.

A running stroke of the pumping unit load end includes an upward stroke and a downward stroke. Each of the abovementioned steps may be executed in either upward stroke or the downward stroke. Therefore, in one running stroke of the pumping unit load end, the neutral position signal triggering step may further be divided into the following steps.

At an upward neutral position signal triggering step, when the pumping unit load end runs to the midpoint position of the upward stroke, the pumping unit position sensor system generates an upward neutral position signal, and the pumping unit load end enters the upper-range upward running stroke section.

In a downward neutral position signal triggering step, when the pumping unit load end runs to the midpoint position of the downward stroke, the pumping unit position sensor system generates a downward neutral position signal, and the pumping unit load end enters the lower-range downward running stroke section.

The at least one stroke parameter determination step may further be divided into the following steps.

At an upper-range upward stroke parameter determination step, under triggering of the upward neutral position signal, the numerical value of the stroke counter is cleared and the stroke counter is adopted to perform recounting to obtain the at least one required running stroke parameter of the motor according to the distance value of the pumping unit load end in the upper-range upward running stroke section.

At a lower-range downward stroke parameter determination step of the pumping unit load end, under triggering of the downward neutral position signal, the numerical value of the stroke counter is cleared and the stroke counter is adopted to perform recounting to obtain the at least one required running stroke parameter of the motor according to the distance value of the pumping unit load end in the lower-range downward running stroke section.

The running step may further be divided into the following steps.

At an upper-range upward running step, the motor is controlled to start running according to the at least one required running stroke parameter of the motor, and the motor is controlled to be reversed to enter the upper-range downward running stroke section after completing running according to the at least one required running stroke parameter or under triggering of the upper position signal.

At a lower-range downward running step, the motor is controlled to start running according to the at least one required running stroke parameter of the motor, and the motor is controlled to be reversed to enter the lower-range upward running stroke section after completing running according to the at least one required running stroke parameter or under triggering of the lower position signal.

Since a cyclic working sequence of the pumping unit load end is the upper-range upward running stroke section—the upper-range downward running stroke section—the lower-range downward running stroke section—the lower-range upward running stroke section—the upper-range upward running stroke section, a cyclic running step of the steps includes: the upward neutral position triggering step, the upper-range upward pulse determination step, the upper-range upward running step, the downward neutral position signal triggering step, the lower-range downward pulse determination step and the lower-range downward running step.

The above are the optional embodiments of the control method of the present disclosure. Through the above-mentioned method, stroke regulation is performed on a long-stroke pumping unit, and through a neutral position calibration function, two calibration opportunities are provided for each stroke of the pumping unit, and stroke changes brought by motor belt transmission, load belt extension and retraction and other elastic links are controlled within a minimum range. Furthermore, through the stroke determination step, failures caused by running of the pumping unit load end beyond physical limit positions are avoided.

In an optional embodiment, a driving system of the pumping unit may be a reversing variable-speed motor system. The reversing variable-speed motor system includes the motor and a motor controller. The motor controller controls the at least one running parameter of the motor. The at least one running parameter including an initial rotation speed, the stroke, motor reversing, reversing time point, an overload coefficient, overload protection time period and the like. A rotation speed is set to determine an operating speed of the motor. The initial speed of the motor, a speed in an upper-range stroke and a speed in a lower-range stroke may be set respectively, and in each independent stroke, the rotation speed of the motor is variable. Reversing of the motor forms a one-to-one corresponding relationship with a running direction of the pumping unit load end, and reversing of the motor may be set to control the running direction of the pumping unit load end. Since the operating speed and the stroke of the motor forms a corresponding relationship with a movement distance of the pumping unit load end, and the operating speed of the motor forms a corresponding relationship with at least one running stroke parameter of the motor, the at least one required running stroke parameter of the motor may be calculated through a distance value in the upper-range stroke. Cyclic running time period of the pumping unit load end in each stroke is set through a stroke frequency setting and the reversing time point. The stroke frequency and the reversing time period may be manually written through the motor controller or the reversing time point may be automatically optimized according to the speed of the motor through a control program of the motor controller, thereby implementing short-time forced reversing or smooth reversing according to the rotation speed of the motor and meeting requirements of different working conditions. The above parameters are set to ensure correct protection setting of the motor and realize overload and under-voltage signal protection functions. The above parameters of the motor are regulated to control running of the pumping unit load end of the pumping unit in the whole stroke.

In an optional embodiment, at least one of the neutral position signal, the upper position signal and the lower position signal, an upward limit position signal and a downward limit position signal is generated through the pumping unit position sensor system. The stroke and running direction of the pumping unit load end may be calculated according to a triggering state of the pumping unit position sensor system and reversing of the motor.

FIG. 4 is a workflow chart of a control method according to a second optional embodiment of the present disclosure. As shown in FIG. 4, the power control method for a vertical pumping unit includes the following steps.

At an initialization step S1, after the vertical pumping unit is energized, power-on self-test is performed, and if an indicator lamp is abnormal, whether each component and wire are normal or not is checked. When each indicator lamp is normal and a screen of a Programmable Logic Controller (PLC) displays normally, it is indicated that the system completes self-test and may be smoothly started.

At a parameter setting step, an initial rotation speed, reversing time point, overload coefficient and overload protection time period of a motor are set on a switched reluctance motor controller to ensure correct protection setting of the motor. Then, at least one stroke running parameter is set in an operating interface of the PLC, and the at least one stroke running parameter includes a distance value in an upper-range stroke and a distance value in a lower-range stroke. After the pumping unit is mounted in place on the spot, stroke correction is further required to be performed according to guidance before first-time energizing for running.

At a running starting step, the pumping unit is started, and the set rotation speed parameter of the motor is read. The switched reluctance motor operates to drive a hanging load at a pumping unit load end at a lower end of a belt to move upwards. In such case, the rotation speed of the switched reluctance motor may be regulated through a rotation speed regulation knob, thereby regulating a running speed of the pumping unit load end.

At an upward neutral position signal triggering step S2, the pumping unit load end runs to a midpoint position of an upward stroke, and a pumping unit position sensor system generates an upward neutral position signal.

At an upper-range upward stroke determination step S3, under triggering of the upward neutral position signal, a numerical value of a stroke counter configured to count at least one running stroke parameter of the motor is cleared, and the PLC calculates at least one required running stroke parameter of the motor according to a preset distance value of the pumping unit load end in an upper-range upward running stroke section.

At an upper-range upward running step S4, the motor is controlled to start running according to the at least one required running stroke parameter of the motor. The running step S4 includes an upper/lower position signal determination step S40, a pulse control reversing step S41 and a forced reversing step S42.

At the upper/lower position signal determination step S40, whether the pumping unit position sensor system generates the upper position signal or not is determined.

When determining that the pumping unit position sensor system generates the upper position signal, the forced reversing step S42 is executed. At the forced reversing step S42, the motor is controlled to execute a forced reversing operation according to the upper position signal, and the pumping unit load end runs downwards.

When determining that the pumping unit position sensor system does not generate the upper position signal, the stroke control reversing step S41 is executed. At the stroke control reversing step S41, the motor is controlled to be reversed for running after completing running according to the at least one required running stroke parameter, and the pumping unit load end runs downwards.

At a downward neutral position signal triggering step S2, the pumping unit load end runs to a midpoint position of a downward stroke, the pumping unit position sensor system generates a downward neutral position signal, and the pumping unit load end enters a lower-range downward running stroke section.

At a lower-range downward stroke determination step S3, under triggering of the downward neutral position signal, the numerical value of the stroke counter configured to count the running stroke of the motor is cleared. The PLC adopts the stroke counter to perform recounting to obtain the at least one required running stroke parameter according to a preset distance value of the pumping unit load in the lower-range downward running stroke section.

At a lower-range downward running step S4, the motor is controlled to start running according to the at least one required running stroke parameter of the motor.

The running step S4 includes the upper/lower position signal determination step S40, the stroke control reversing step S41 and the forced reversing step S42.

At the upper/lower position signal determination step S40, whether the pumping unit position sensor system generates the lower position signal or not is determined.

When determining that the pumping unit position sensor system generates the lower position signal, the forced reversing step S42 is executed. At the forced reversing step S42, the motor is controlled to execute the forced reversing operation according to the lower position signal, and the pumping unit load end runs upwards to enter a next working cycle.

When determining that the pumping unit position sensor system does not generate the lower position signal, the stroke control reversing step S41 is executed. At the stroke control reversing step S41, the motor is controlled to be reversed for running after completing running according to the at least one required running stroke parameter, and the pumping unit load end runs upwards to enter the next working cycle.

In the whole running process of the pumping unit, if a failure occurs, a limit position signal triggering step S5 is executed at first to generate an upward limit position signal or a downward limit position signal; and then a forced de-energizing step S6 is executed to control the whole pumping unit to be forcibly de-energized according to the upward limit position signal or the downward limit position signal.

FIG. 5 is a workflow chart of a control method according to a third optional embodiment of the present disclosure. As shown in FIG. 5, the power control method for a vertical pumping unit includes the following steps.

At an initialization step, after the vertical pumping unit is energized, power-on self-test is performed, and if an indicator lamp is abnormal, whether each component and wire are normal or not is checked. When each indicator lamp is normal and a screen of a PLC displays normally, it is indicated that the system completes self-test and may be smoothly started.

At a parameter setting step, an initial rotation speed, reversing time point, overload coefficient and overload protection time period of a motor are set on a motor controller to ensure correct protection setting of the motor. Then, at least one stroke running parameter is set in an operating interface of the PLC, and the at least one stroke running parameter includes a distance value in an upper-range stroke and a distance value in a lower-range stroke. After the pumping unit is mounted in place on the spot, stroke correction is further required to be performed according to guidance before first-time energizing for running.

At a running starting step, the pumping unit is started, and the set rotation speed parameter of the motor is read. The motor operates to drive a hanging load at a pumping unit load end at a lower end of a belt to move downwards. In such case, the rotation speed of the motor may be regulated through a rotation speed regulation knob, thereby regulating a running speed of the pumping unit load end.

At a first signal determination step, whether a pumping unit position sensor system generates a neutral position signal or not is determined.

When determining that the pumping unit position sensor system does not generate the neutral position signal, a neutral position signal triggering step is executed.

When determining that the pumping unit position sensor system generates the neutral position signal, a forced reversing step is executed. At the forced reversing step, the motor is controlled to execute a forced reversing operation according to an upper position signal.

At a downward neutral position signal triggering step, the pumping unit load end runs to a midpoint position of a downward stroke, and the position sensor system generates a downward neutral position signal.

At a lower-range downward stroke determination step, under triggering of the downward neutral position signal, a numerical value of a stroke counter configured to count running strokes of the motor is cleared, and the PLC calculates at least one required running stroke parameter of the motor according to a preset distance value of the pumping unit load end in a lower-range downward running stroke section.

At a lower-range downward running step, the motor is controlled to start running according to the at least one required running stroke parameter of the motor. The running step includes an upper/lower position signal determination step, a stroke control reversing step and the forced reversing step.

At the upper/lower position signal determination step, whether the pumping unit position sensor system generates the lower position signal or not is determined.

When determining that the pumping unit position sensor system triggers the lower position signal, the forced reversing step is executed. At the forced reversing step, the motor is controlled to execute the forced reversing operation according to the lower position signal, and the pumping unit load end runs upwards.

When determining that the pumping unit position sensor system does not generate the lower position signal, the stroke control reversing step is executed. At the stroke control reversing step, the motor is controlled to be reversed for running after completing running according to the at least one required running stroke parameter, and the pumping unit load end runs upwards.

At an upward neutral position signal triggering step, the pumping unit load end runs to a midpoint position of an upward stroke, the position sensor system generates an upward neutral position signal, and the pumping unit load end enters an upper-range upward running stroke section.

At an upper-range upward pulse determination step, under triggering of the upward neutral position signal, the numerical value of the stroke counter configured to count the running stroke of the motor is cleared. The PLC adopts the stroke counter to perform recounting to obtain the at least one required running stroke parameter according to a preset distance value of the pumping unit load in the upper-range upward running stroke section.

At an upper-range upward running step, the motor is controlled to start running according to the at least one required running stroke parameter of the motor.

The running step includes the upper/lower position signal determination step, the stroke control reversing step and the forced reversing step.

At the upper/lower position signal determination step, whether the pumping unit position sensor system generates the upper position signal or not is determined.

When determining that the pumping unit position sensor system generates the upper position signal, the forced reversing step is executed. At the forced reversing step, the motor is controlled to execute the forced reversing operation according to the upper position signal, and the pumping unit load end runs downwards to enter the next working cycle.

When determining that the pumping unit position sensor system does not generate the upper position signal, the stroke control reversing step is executed. At the stroke control reversing step, the motor is controlled to be reversed for running after completing running according to the at least one required running stroke parameter, and the pumping unit load end runs downwards to enter the next working cycle.

In the whole running process of the pumping unit load end, if a failure occurs, a limit position signal triggering step is executed at first to generate an upward limit position signal or a downward limit position signal; and then a forced de-energizing step is executed to control the whole pumping unit to be forcibly de-energized according to the upward limit position signal or the downward limit position signal.

It is to be noted that the upper position signal, the neutral position signal and the lower position signal may be generated in multiple manners, which will not be specifically limited in the present disclosure.

In an optional embodiment, the stroke and running direction of the pumping unit load end are calculated under assistance of signals generated by an upper sprocket and the position sensor system arranged at an upper portion of a rack of the pumping unit, thereby determining that the stroke that the pumping unit load end may enter and obtaining the required running distance value at the stroke determination step. The upper sprocket is supported by an upper sprocket shaft, and a position proportional speed reducer is coupled to the upper sprocket shaft. The position proportional speed reducer is positioned at the upper portion of the rack, and includes a rotating portion and a fixed portion. The rotating portion includes a large gear and a position sensor triggering device, the position sensor triggering device rotates together with the large gear, and the large gear is meshed with a small gear coupled with the upper sprocket shaft. The fixed portion includes an upper limit position sensor, upper position sensor, neutral position sensor, lower position sensor and lower limit position sensor which are sequentially arranged in a circumferential direction. The upper limit position sensor or the lower limit position sensor is triggered to de-energize the pumping unit. Of course, in other implementation modes, the fixed portion may also not include the upper limit position sensor and the lower limit position sensor.

When the pumping unit is in a working state, the pumping unit load end reciprocates at a high frequency, and the upper sprocket reciprocally rotates faster. The small gear on a driven sprocket shaft is relatively high in rotation speed. Due to existence of a relatively high transmission ratio, the large gear meshed with the small gear is relatively low in rotation speed. In a process of rotating together with the large gear, the position sensor triggering device triggers corresponding position sensors according to different rotation positions. When the pumping unit load end is at a midpoint position of a stroke, the position sensor triggering device correspondingly triggers the neutral position sensor. When the pumping unit load end is at a lower reversing position of the stroke, the position sensor triggering device correspondingly triggers the lower position sensor. When the pumping unit load end is at an upper reversing position of the stroke, the position sensor triggering device correspondingly triggers the upper position sensor. When the pumping unit load end is at a lower limit position of the stroke, the position sensor triggering device correspondingly triggers the lower limit position sensor. When the pumping unit load end is at an upper limit position of the stroke, the position sensor triggering device correspondingly triggers the upper limit position sensor. Positions of the upper limit position sensor, the upper position sensor, the neutral position sensor, the lower position sensor and the lower limit position sensor are obtained by stroke correction. At least one mechanical position signal of the above speed reduction transmission device may be extracted to indicate a circumferential position of the upper sprocket shaft and simultaneously display a stroke position of the pumping unit load end.

At the initialization step, reversing time point is written through the motor controller or the reversing time point is automatically optimized according to the speed of the motor through a control program of the motor controller, thereby controlling the operating speed of the motor. Different reversing time point may be set for the motor in four strokes. The reversing time point may be written to implement short-time forced reversing, ensure smoother reversing and meet requirements of different working conditions. The abovementioned parameters may be regulated by use of a touch screen, a knob or a button.

From the above description, it can be seen that the abovementioned embodiments of the present disclosure have the following technical effects.

Through the control method of the present disclosure, stroke regulation is performed on a long-stroke pumping unit, and by a neutral position calibration and compensation function, two calibration and compensation opportunities are provided for each stroke of the pumping unit, and stroke changes brought by motor belt transmission, load belt extension and retraction and other elastic links are controlled within a minimum range. Furthermore, through the stroke determination step, failures caused by running of the pumping unit load end beyond dead point positions are avoided.

Multiple steps and functions disclosed in the specification and the claims may not be explained to be disclosed in a specific sequence, and the multiple disclosed steps and functions are not limited to the specific sequence, unless these steps and functions may not be exchanged for technical reasons. In addition, in the embodiments, a single step may include or be divided into multiple sub-steps. The method disclosed in the specification and the claims may be implemented into a device having components configured to execute each corresponding step in the method.

The above are exemplary embodiments of the present disclosure and not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modifications, equivalent replacements, improvements and the like made within the spirit and principle of the present disclosure shall fall within the scope of protection of the present disclosure. 

What is claimed is:
 1. A control method for a vertical pumping unit, a load end of the vertical pumping unit being driven by a motor of a driving system to reciprocate for an upward stroke and a downward stroke, the control method comprising: setting at least one initialization parameter of the motor for controlling the pumping unit load end to start running from an initial position; when the pumping unit load end runs to a midpoint position of the upward stroke or a midpoint position of the downward stroke, generating a neutral position signal; under triggering of the neutral position signal, clearing a numerical value of a counter configured to count running strokes of the motor, and adopting the counter to perform recounting to obtain at least one required running stroke parameter of the motor according to a preset required running distance value of the pumping unit load end; and controlling the motor to start running according to the at least one required running stroke parameter of the motor.
 2. The control method as claimed in claim 1, further comprising: when the pumping unit load end runs to a forced reversing position at a predetermined distance away from a limit position of the upward stroke, controlling a pumping unit position sensor system to generate an upper position signal, or, when the pumping unit load end runs to a forced reversing position at the predetermined distance away from a limit position of the downward stroke, controlling the pumping unit position sensor system to generate a lower position signal.
 3. The control method as claimed in claim 2, further comprising: when controlling the motor to start running according to the at least one required running stroke parameter of the motor, determining whether the pumping unit position sensor system generates the upper position signal or the lower position signal or not.
 4. The control method as claimed in claim 3, further comprising: when determining that the pumping unit position sensor system generates the upper position signal or the lower position signal, controlling the motor to execute a forced reversing operation according to the upper position signal or the lower position signal.
 5. The control method as claimed in claim 3, further comprising: when determining that a running position of the pumping unit load end does not reach a position of the upper position signal or the lower position signal, controlling the motor to be reversed for running after completing running according to the at least one required running stroke parameter of the motor.
 6. The control method as claimed in claim 2, further comprising: after setting the at least one initialization parameter for controlling the pumping unit load end to start running from the initial position, determining whether the pumping unit position sensor system generates the upper position signal or the lower position signal or not; when determining that the pumping unit position sensor system does not trigger the upper position signal or the lower position signal and when the pumping unit load end runs to the midpoint position of the upward stroke or the midpoint position of the downward stroke, controlling the pumping unit position sensor system to generate a neutral position signal; and when determining that the pumping unit position sensor system generates the upper position signal or the lower position signal, controlling the motor to execute the forced reversing operation according to the upper position signal or the lower position signal.
 7. The control method as claimed in claim 2, further comprising: when the pumping unit load end runs to the limit position of the upward stroke, controlling the pumping unit position sensor system to generate an upward limit position signal, or, when the pumping unit load end runs to the limit position of the downward stroke, controlling the pumping unit position sensor system to generate a downward limit position signal.
 8. The control method as claimed in claim 7, further comprising: controlling the vertical pumping unit to be forcibly de-energized according to the upward limit position signal or the downward limit position signal.
 9. The control method as claimed in claim 1, further comprising: dividing the upward stroke into a lower-range upward running stroke section and an upper-range upward running stroke section according to the midpoint position of the upward stroke.
 10. The control method as claimed in claim 9, further comprising: dividing the downward stroke into an upper-range downward running stroke section and a lower-range downward running stroke section according to the midpoint position of the downward stroke.
 11. The control method as claimed in claim 10, further comprising: the required running distance value of the pumping unit load end being a distance value in the upper-range upward running stroke section or a distance value in the lower-range downward running stroke section.
 12. The control method as claimed in claim 11, wherein setting the at least one initialization parameter for controlling the pumping unit load end to start running from the initial position comprises: setting at least one running parameter of the motor and at least one stroke parameter of the vertical pumping unit, the at least one stroke parameter comprising the distance value in the upper-range upward running stroke section and the distance value in the lower-range downward running stroke section; and controlling the motor to run according to the at least one running parameter and driving, through a mechanical transmission device of the pumping unit, the pumping unit load end to run, the mechanical transmission device comprising a belt, a gear speed reducer and a chain transmission system.
 13. The control method as claimed in claim 12, wherein generating the neutral position signal when the pumping unit load end runs to the midpoint position of the upward stroke or the midpoint position of the downward stroke comprises one of the followings: when the pumping unit load end runs to the midpoint position of the upward stroke, generating an upward neutral position signal, and entering the upper-range upward running stroke section; and when the pumping unit load end runs to the midpoint position of the downward stroke, generating a downward neutral position signal, and entering the lower-range upward running stroke section.
 14. The control method as claimed in claim 13, wherein under triggering of the neutral position signal, clearing the numerical value of the stroke counter and adopting the stroke counter to perform recounting to obtain the at least one required running stroke parameter of the motor according to the required running distance value of the pumping unit load end comprises one of the followings: under triggering of the upward neutral position signal, clearing the numerical value of the stroke counter and adopting the stroke counter to perform recounting to obtain the at least one required running stroke parameter of the motor according to the distance value of the pumping unit load end in the upper-range upward running stroke section; and under triggering of the downward neutral position signal, clearing the numerical value of the stroke counter and adopting the stroke counter to perform recounting to obtain the at least one required running stroke parameter of the motor according to the distance value of the pumping unit load end in the lower-range downward running stroke section.
 15. The control method as claimed in claim 14, wherein controlling the motor to start running according to the at least one required running stroke parameter of the motor comprises one of the followings: controlling the motor to start running according to the at least one required running stroke parameter of the motor, and controlling the motor to be reversed to enter the upper-range downward running stroke section after completing running according to the at least one required running stroke parameter or under triggering of the upper position signal; and controlling the motor to start running according to the at least one required running stroke parameter of the motor, and controlling the motor to be reversed to enter the lower-range upward running stroke section after completing running according to the at least one required running stroke parameter or under triggering of the lower position signal.
 16. The control method as claimed in claim 2, wherein at least one of the neutral position signal, the upper position signal and the lower position signal, an upward limit position signal and a downward limit position signal is generated through the pumping unit position sensor system.
 17. The control method as claimed in claim 1, further comprising: acquiring a first circumferential azimuth signal of an upper sprocket shaft of a driving system in a rotating process; and calculating a stroke position of the pumping unit load end according to the first circumferential azimuth signal and a rotation direction of the motor.
 18. The control method as claimed in claim 17, further comprising: acquiring a second circumferential azimuth signal of a gear in a transmission relationship with the upper sprocket shaft in the rotating process; and calculating the stroke position of the pumping unit load end according to the second circumferential azimuth signal and the rotation direction of the motor.
 19. The control method as claimed in claim 1, wherein the motor is a stepless speed regulation motor that is reversed for reciprocation.
 20. The control method as claimed in claim 12, wherein the at least one running parameter of the motor is transmitted, monitored and regulated through a remote communication control component. 